This invention relates to methods and apparatus for controlling the operation of an internal combustion engine, in particular an engine used for a motor vehicle.
In order to operate a motor vehicle internal combustion engine with minimum energy consumption, the engine must be operated in a range of engine rotational speeds and loads which are favorable for fuel consumption. Thus the operating points of the engine, where the fuel consumption is substantially higher than necessary to accommodate the output load must be avoided.
The apparatus described in U.S. Pat. No. 3,916,854 to Barton describes an arrangement wherein a gas pedal for motor vehicle is connected to a throttle by a control apparatus, which is operated in connection with an engine speed sensor. By sensing the rotational speed of the engine, and by the use of a cam and cam follower or electronic storage and computing means, the throttle opening is allowed to reach only a specific position at each speed corresponding to the most efficient operating condition for the engine rotation speed and load demanded. These positions for the different speeds are stored in the cam or electronic storage means and define a predetermined curve in the power-speed-diagram of the engine. When the operator actuates the gas pedal, an adjustment of the throttle takes place in accordance with the actual rotational speed of the engine. For each rotational speed the output associated with that speed according to the predetermined curve is obtained by a suitable adjustment of the throttle. The output and speed of the engine thus become greater as the operating point of the engine moves along the predetermined curve, until finally the setting of the throttle is reached which corresponds to the position of the gas pedal. Then the operating point travels along the line of constant throttle setting to its intersection with a line of resistance to motion (road resistance), that is, it leaves the preassigned curve. The final setting of the throttle is thus determined by positioning the gas pedal, and ultimately reached along the preassigned curve by automatic adjustment.
It is an object of the present invention to provide a method for operating an internal combustion engine an a device for practicing that method to preclude operating points of the engine in the power output-rotational speed diagram which are disadvantageous in terms of fuel consumption.